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Cover of Addressing Head–on Conflicts Towards Safe System Alignment: A Compendium of Treatments
Addressing Head–on Conflicts Towards Safe System Alignment: A Compendium of Treatments
  • Publication no: AP-R717-24
  • ISBN: 978-1-922994-48-6
  • Published: 29 October 2024

The purpose of this study is to identify contemporary guidance and research on median treatments that contribute to the ultimate elimination of death and serious injury as a result of head-on crashes. The median treatments considered range from treatments that virtually eliminate death and serious injury to lower scale solutions that achieve safety gains at lower costs.

This report references and builds on relevant Australasian and international literature gathered through internet and database searches and recommendations from the project working group.

An extensive literature review identified and explored a graduated suite of median treatment options. The findings of the review have informed the development of guidance to support road design practitioners to make informed and consistent decisions when selecting and designing median treatments, weighing their respective risks and benefits.

The report concludes with a discussion of the implications of the research findings for road design.

  • Summary
  • 1. Introduction
    • 1.1 Purpose
    • 1.2 Scope
    • 1.3 Methodology
      • 1.3.1 Austroads and member agency guidelines
      • 1.3.2 Literature searches
      • 1.3.3 Case studies
      • 1.3.4 Modelling of crash rates
    • 1.4 Median treatments and the Safe System approach
  • 2. Pavement Markings
    • 2.1 Australasian practice
    • 2.2 International practice
    • 2.3 Effectiveness
      • 2.3.1 Australian and New Zealand evaluations
      • 2.3.2 International evaluations of pavement markings
    • 2.4 Limitations identified in the literature review
    • 2.5 Case study - Toodyay-Bindi Bindi Road, Western Australia
    • 2.6 Case study - Clackline-Toodyay Road, Western Australia
    • 2.7 Case study - Monaro Highway, NSW
      • 2.7.1 Key facts
      • 2.7.2 Road description
      • 2.7.3 Treatment details
      • 2.7.4 Study methodology
      • 2.7.5 Safety evaluation and outcomes
      • 2.7.6 Limitations
      • 2.7.7 Conclusions
    • 2.8 Case study - Michigan, USA
      • 2.8.1 Key facts
      • 2.8.2 Road description
      • 2.8.3 Study methodology
      • 2.8.4 Safety evaluation and outcomes
      • 2.8.5 Limitations
    • 2.9 Conclusions
  • 3. Audio Tactile Line Marking
    • 3.1 Australasian practice
    • 3.2 International practice
    • 3.3 Effectiveness
      • 3.3.1 Australian and New Zealand evaluations
      • 3.3.2 International evaluations
    • 3.4 Limitations identified in the literature review
    • 3.5 Case study - mass centreline ATLM rollout, Victoria
      • 3.5.1 Key facts
      • 3.5.2 Road description
      • 3.5.3 Treatment details
      • 3.5.4 Study methodology
      • 3.5.5 Safety evaluation and outcomes
      • 3.5.6 Limitations
    • 3.6 Case studies - various states, USA
      • 3.6.1 Key facts
      • 3.6.2 Road description
      • 3.6.3 Treatment details
      • 3.6.4 Study methodology
      • 3.6.5 Safety evaluation and outcomes
      • 3.6.6 Limitations
    • 3.7 Conclusions
  • 4. Wide Centre Line Treatment
    • 4.1 Australasian practice
    • 4.2 International Practice
    • 4.3 Effectiveness
      • 4.3.1 Australian and New Zealand evaluations
      • 4.3.2 International evaluations
    • 4.4 Limitations identified in the literature review
    • 4.5 Case study - Newell Highway, NSW
      • 4.5.1 Key facts
      • 4.5.2 Road description
      • 4.5.3 Treatment details
      • 4.5.4 Study methodology
      • 4.5.5 Safety evaluation and outcomes
      • 4.5.6 Limitations
      • 4.5.7 Conclusions
    • 4.6 Case study - Pacific Highway and New England Highway, NSW
      • 4.6.1 Key facts
      • 4.6.2 Study methodology
      • 4.6.3 Safety evaluation and outcomes
      • 4.6.4 Limitations
      • 4.6.5 Conclusions
    • 4.7 Case study - Bruce Highway, Queensland
      • 4.7.1 Key facts
      • 4.7.2 Road description
      • 4.7.3 Treatment details
      • 4.7.4 Study methodology
      • 4.7.5 Safety evaluation and outcomes
      • 4.7.6 Limitations
      • 4.7.7 Conclusions
    • 4.8 Case study - Anglesea Road and Great Ocean Road, Victoria
      • 4.8.1 Key facts
      • 4.8.2 Road description
      • 4.8.3 Treatment details
      • 4.8.4 Study methodology
      • 4.8.5 Safety evaluation and outcomes
      • 4.8.6 Limitations
      • 4.8.7 Conclusions
    • 4.9 Conclusions
  • 5. Narrow Median with Flexible Barriers
    • 5.1 Australasian practice
      • 5.1.1 Median width
      • 5.1.2 Carriageway width
      • 5.1.3 Length of treatment
      • 5.1.4 Choice of flexible barrier type
      • 5.1.5 Warrants
    • 5.2 International practice
    • 5.3 Effectiveness
      • 5.3.1 Evaluations in Austroads publications
      • 5.3.2 Australasian evaluations
      • 5.3.3 International research
      • 5.3.4 Barrier type
    • 5.4 Considerations identified in the literature review
      • 5.4.1 Barrier deflection
      • 5.4.2 Heavy vehicles
      • 5.4.3 Barrier penetration
      • 5.4.4 Road geometry
      • 5.4.5 Access
      • 5.4.6 Maintenance
      • 5.4.7 Continuity of protection
      • 5.4.8 Motorcycles
    • 5.5 Case Study - Pacific and New England Highways, NSW
      • 5.5.1 Key facts
      • 5.5.2 Road description
      • 5.5.3 Treatment details
      • 5.5.4 Study methodology
      • 5.5.5 Safety evaluation and outcomes
      • 5.5.6 Limitations
      • 5.5.7 Conclusions
    • 5.6 Case study - Pacific Highway, NSW
      • 5.6.1 Key facts
      • 5.6.2 Road description
      • 5.6.3 Treatment details
      • 5.6.4 Study methodology
      • 5.6.5 Safety evaluation and outcomes
      • 5.6.6 Limitations
      • 5.6.7 Conclusion
    • 5.7 Case study - Centennial Highway, New Zealand
      • 5.7.1 Key facts
      • 5.7.2 Road description
      • 5.7.3 Treatment details
      • 5.7.4 Study methodology
      • 5.7.5 Safety evaluation and outcomes
      • 5.7.6 Limitations
      • 5.7.7 Conclusions
    • 5.8 Case study - State Highway 1, Rangiriri, New Zealand
      • 5.8.1 Key facts
      • 5.8.2 Road description
      • 5.8.3 Treatment details
      • 5.8.4 Study methodology
      • 5.8.5 Safety evaluation and outcomes
      • 5.8.6 Limitations
      • 5.8.7 Conclusion
    • 5.9 Case study - Victor Harbor Road, South Australia
      • 5.9.1 Key facts
      • 5.9.2 Road description
      • 5.9.3 Treatment details
      • 5.9.4 Study methodology
      • 5.9.5 Safety evaluation and outcomes
      • 5.9.6 Limitations
      • 5.9.7 Conclusions
    • 5.10 Case studies - various sites, Western Australia
      • 5.10.1 Key facts
      • 5.10.2 Road description
      • 5.10.3 Treatment details
      • 5.10.4 Study methodology
      • 5.10.5 Safety evaluation and outcomes
      • 5.10.6 Limitations
      • 5.10.7 Conclusions
    • 5.11 Case studies - various major highways, Victoria
      • 5.11.1 Key facts
      • 5.11.2 Road description
      • 5.11.3 Treatment details
      • 5.11.4 Study methodology
      • 5.11.5 Safety evaluation and outcomes
      • 5.11.6 Limitations
      • 5.11.7 Conclusions
    • 5.12 Case study - Princes Highway East, Victoria
      • 5.12.1 Key facts
      • 5.12.2 Road description
      • 5.12.3 Treatment details
      • 5.12.4 Study methodology
      • 5.12.5 Safety evaluation and outcomes
      • 5.12.6 Limitations
    • 5.13 Conclusions
  • 6. Narrow Median with Stiffer Steel Barriers
    • 6.1 Australasian practice
    • 6.2 International practice
    • 6.3 Effectiveness
    • 6.4 Limitations identified in the literature review
    • 6.5 Case study - Picton Road, New South Wales
      • 6.5.1 Key facts
      • 6.5.2 Road description
      • 6.5.3 Treatment details
      • 6.5.4 Study methodology
      • 6.5.5 Safety evaluation and outcomes
      • 6.5.6 Limitations
    • 6.6 Case study - Princes Highway, New South Wales
      • 6.6.1 Key facts
      • 6.6.2 Road description
      • 6.6.3 Treatment details
      • 6.6.4 Study methodology
      • 6.6.5 Safety evaluation and outcomes
      • 6.6.6 Limitations
    • 6.7 Conclusions
  • 7. Narrow Median with Concrete Barrier
    • 7.1 Australasian practice
    • 7.2 International practice
    • 7.3 Effectiveness
    • 7.4 Limitations identified in the literature review
    • 7.5 Conclusions
  • 8. Wide Median With and Without a Barrier
    • 8.1 Australasian practice
      • 8.1.1 Austroads publications
      • 8.1.2 Jurisdictional practices
    • 8.2 International practice
    • 8.3 Effectiveness
      • 8.3.1 Australasian evaluations
      • 8.3.2 International evaluations
    • 8.4 Limitations identified in the literature review
    • 8.5 Conclusions
  • 9. Other Treatments
    • 9.1 Road widening
    • 9.2 Raised medians
    • 9.3 Painted medians
    • 9.4 Median turning bays
    • 9.5 Overtaking lanes
    • 9.6 Reduced speed limits
  • 10. Guidance on Choice of Median Treatment
    • 10.1 Staging interventions
    • 10.2 Conclusions
  • 11. Crash Modification Factors
    • 11.1 Methodology
    • 11.2 Crash modification factors for pavement markings
    • 11.3 Crash modification factors for audio tactile line marking (ATLM)
    • 11.4 Crash modification factors for wide centre line treatment
    • 11.5 Crash modification factors for narrow median with wire rope safety barrier
    • 11.6 Crash modification factors for narrow median with flexible w-beam barrier
    • 11.7 Overview of the crash modification factors
  • 12. Evaluating the Head-On Crash Risk
    • 12.1 Encroachment frequency in the Austroads Guide to Road Design Part 6
    • 12.2 Exposure adjustments for narrow median treatments without a barrier
    • 12.3 Frequency of head-on crashes on undivided rural roads in the Austroads Guide to Road Design Part 6
    • 12.4 Likelihood function in the Austroads Guide to Road Design Part 6
    • 12.5 Likelihood of FSI head-on crashes in the Austroads Guide to Road Design Part 6
    • 12.6 Likelihood adjustments for narrow median treatments without a barrier
    • 12.7 Exposure and likelihood adjustments for narrow median treatments with a barrier
    • 12.8 Likely severity of a head-on crash
    • 12.9 Conclusions
  • 13. Implications for Road Design
    • 13.1 Pavement markings
      • 13.1.1 Enhanced dividing lines
    • 13.2 Audio tactile line marking
      • 13.2.1 Application
      • 13.2.2 Location of ATLM relative to linemarking
      • 13.2.3 Effectiveness
      • 13.2.4 Dimensions
      • 13.2.5 Noise
      • 13.2.6 Motorcyclists
      • 13.2.7 Bicycles
      • 13.2.8 Maintenance
    • 13.3 Wide centre line treatment
      • 13.3.1 Application
      • 13.3.2 Effectiveness
      • 13.3.3 Dimensions
      • 13.3.4 Maintenance and access
      • 13.3.5 Pavement markings and ATLM
    • 13.4 Narrow median with flexible barriers
      • 13.4.1 Application
      • 13.4.2 Effectiveness
      • 13.4.3 Median width and barrier lateral location
      • 13.4.4 Width between barriers
      • 13.4.5 Choice of barrier system
      • 13.4.6 Barrier terminal treatments
      • 13.4.7 Sight distance
      • 13.4.8 Maintenance
      • 13.4.9 Motorcyclists
      • 13.4.10 Barrier penetration and heavy vehicles
    • 13.5 Narrow median with stiffer steel barriers
    • 13.6 Narrow median with concrete barrier
    • 13.7 Other learnings
  • 14. Sight Distance Restricted by a Barrier in a Narrow Median
  • 15. Conclusions
  • References
  • Appendix A. Evaluating Exposure Factors
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